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From: John Fields on 26 Mar 2010 09:43
On 26 Mar 2010 08:17:53 GMT, Jasen Betts <jasen(a)xnet.co.nz> wrote:

>On 2010-03-25, George Herold <ggherold(a)gmail.com> wrote:
>> On Mar 25, 9:52�am, N0S...(a)daqarta.com (Bob Masta) wrote:
>
>>
>> Thank Bob, my Boss has looked at a whole bunch of different
>> commercial units from Protek, B&K, I'm not sure if we looked at any
>> from Instek. It looks like we are going to build our own. At least
>> then we know what is going on inside.
>
>it seems to me that frequency counters are for measuring singals that
>have a frequency that can be measured un Hz. the randomly distributed
>pulses from a photomultiplier or a geiger tube can't.
>
>> I was playing with a LM393 (dual of the LM339) today. These are a bit
>> slower than I'd like.
>
>what do you expect for less than 25c :)
>
>> Any favorite compartors with perhaps a 50
>> -100nS response time? LM311?
>
>LM319 is at slow end of that range.
>
>hit an online electronic supplier site like digikey, newark, or mouser
>type "comparitor" into the search box and pick your desired parameters

---
I tried it on DigiKey and got back "No records match your search
criteria."

How can that be???

JF
From: Hammy on 26 Mar 2010 09:59
On Fri, 26 Mar 2010 08:43:29 -0500, John Fields
<jfields(a)austininstruments.com> wrote:


>>hit an online electronic supplier site like digikey, newark, or mouser
>>type "comparitor" into the search box and pick your desired parameters
>
>---
>I tried it on DigiKey and got back "No records match your search
>criteria."
>
>How can that be???
>
>JF
Try "comparator". ;-)
From: Peter Bennett on 26 Mar 2010 11:58
On Thu, 25 Mar 2010 13:15:08 -0700 (PDT), George Herold
<ggherold(a)gmail.com> wrote:


>Thank Bob, my Boss has looked at a whole bunch of different
>commercial units from Protek, B&K, I'm not sure if we looked at any
>from Instek. It looks like we are going to build our own. At least
>then we know what is going on inside.
>
>I was playing with a LM393 (dual of the LM339) today. These are a bit
>slower than I'd like. Any favorite compartors with perhaps a 50
>-100nS response time? LM311?
>
>George H.

Have a look at Analog Devices - they have a couple with TTL or CMOS
outputs with 7 - 8 ns propagation delay.



--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
From: whit3rd on 26 Mar 2010 15:57
On Mar 24, 6:31 pm, George Herold <ggher...(a)gmail.com> wrote:

> > Red Lion Controls 'sub-cub' counter...
> > Are you accounting for pile-up effects at high count rates?
>
> Thanks Whit3rd, the 10kHz count rate won't cut it.

It's about 500 kHz (that 10 kHz number was 3V worst case value).

Yeah, the counter is a tad underpowered. Most micros (the PICs
in particular) are weak on counter functions. Best bet is something
with a true counter/timer module, and some preprocessing to
take out pile-up like an up/down pre-counter. Clock UP on input
signal, DOWN iff nonzero, in synchrony with a local clock,
incrementing
the slow counter at a steady rate... a couple of stages of
74F193 can gobble lots of pulses fast, and disgorge at
a compliant rate to the main counter. Your CPU count
is only correct after the pre-counter finishes unloading, of course.
From: George Herold on 26 Mar 2010 17:15
On Mar 26, 11:58 am, Peter Bennett <pete...(a)somewhere.invalid> wrote:
> On Thu, 25 Mar 2010 13:15:08 -0700 (PDT), George Herold
>
> <ggher...(a)gmail.com> wrote:
> >Thank Bob,  my Boss has looked at a whole bunch of different
> >commercial units from Protek, B&K, I'm not sure if we looked at any
> >from Instek.  It looks like we are going to build our own.  At least
> >then we know what is going on inside.
>
> >I was playing with a LM393 (dual of the LM339) today.  These are a bit
> >slower than I'd like.  Any favorite compartors with perhaps a 50
> >-100nS response time?  LM311?
>
> >George H.
>
> Have a look at Analog Devices - they have a couple with TTL or CMOS
> outputs with 7 - 8 ns propagation delay.
>
> --
> Peter Bennett, VE7CEI  
> peterbb4 (at) interchange.ubc.ca  
> GPS and NMEA info:http://vancouver-webpages.com/peter
> Vancouver Power Squadron:http://vancouver.powersquadron.ca

Thanks Peter, I was thinking today that maybe the spec I care about
is the slew rate. I'd like it to get to 5V in about 100nS.. 50V/us.
I don't think I care too much about the propigation delay. (But I
could be wrong... I've only used the slow lm393 for switching low
frequency stuff <1MHz.) I just don't want to miss two close together
pulses.
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